Generally, a capacitive microphone utilizes a capacitance between a pair of electrodes facing each other to transmit an acoustic signal. The capacitive microphone can be manufactured by a semiconductor MEMS process to have an ultra-small size.
A MEMS microphone includes a bendable diaphragm and a back plate facing the diaphragm. The diaphragm is disposed apart from a substrate and the back plate to freely bend upward or downward in response to sound waves incident upon the diaphragm. The diaphragm can be a membrane structure to sense an acoustic pressure to create a displacement. In other words, when the acoustic pressure arrives at the diaphragm, the diaphragm may be bent toward the back plate due to the acoustic pressure. The displacement of the diaphragm can be sensed through a change of capacitance formed between the diaphragm and the back plate. As a result, sound can be converted into an electrical signal for output.
Since such a MEMS microphone is manufactured through a plurality of etching processes for patterning each of a series of layers using a corresponding mask, a manufacturing process for manufacturing the MEMS microphone is complex, requiring many masks for the manufacturing process. The MEMS microphone conventionally has an anchor for supporting the diaphragm apart from the substrate, and a chamber for forming a spacing area between the diaphragm and the back plate. The anchor and the chamber are formed through separate masks and etching processes. This increases the number of masks required for the manufacturing process of the MEMS microphone, which may cause a production cost and a processing time increase.